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A183813 1/81 the number of (n+1) X 3 0..2 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor. 1

%I

%S 8,162,3256,65640,1321860,26630220,536415300,10805642100,217666494900,

%T 4384657426500,88323978892500,1779188631250500,35839769985112500,

%U 721952272492222500,14542924237284172500,292951012163242162500

%N 1/81 the number of (n+1) X 3 0..2 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

%C Column 2 of A183819.

%H R. H. Hardin, <a href="/A183813/b183813.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 15*a(n-1) + 120*a(n-2) - 330*a(n-3).

%F Empirical g.f.: 2*x*(4 + 21*x - 67*x^2) / (1 - 15*x - 120*x^2 + 330*x^3). - _Colin Barker_, Apr 04 2018

%e Some solutions with upper left block zero for 5 X 3:

%e 0 0 0 0 0 0 0 0 1 0 0 2 0 0 1 0 0 0 0 0 2

%e 0 0 2 0 0 1 0 0 1 0 0 1 0 0 0 0 0 2 0 0 2

%e 0 1 0 0 2 0 0 1 2 2 1 1 0 2 2 1 1 0 0 2 2

%e 2 2 1 1 2 0 1 1 2 2 1 2 0 2 2 0 2 1 0 2 1

%e 1 0 1 1 0 2 1 1 1 0 2 1 0 1 0 1 2 2 2 0 0

%Y Cf. A183819.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 07 2011

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Last modified June 17 19:10 EDT 2019. Contains 324198 sequences. (Running on oeis4.)